1. Field of Invention
This invention relates to a manufacturing method of a ball grid array package. More particularly, the present invention is related to a manufacturing method of a ball grid array package in a thin type.
2. Related Art
In this information explosion age, integrated circuits products are used almost everywhere in our daily life, for example electronic products having powerful functions, personalized performance and a higher degree of complexity, and integrated circuits (chip) packaging technology is becoming a limiting factor for the development in packaged integrated circuits of higher performance. Accordingly, semiconductor package designers are struggling to keep pace with the increase in pin count, size limitations, low profile, and other evolving requirements for packaging and mounting integrated circuits.
In the filed of integrated circuits packaging, a ball grid array package (BGA package) is a common type utilized in ICs packaging for that the BGA package has low grounded impedance, low power impedance and more pin counts and is more applicable to high-density ICs package. Usually, BGA package employees a carrier made of a material selected from Bismalesimide-Triazine (BT) and polyimide (PI) to carry a chip and gold wires to make electrical connection between the chip and the carrier. Therein, one of the surface of the carrier has solder balls arranged in a matrix and taken as electrical connection to transmit electrical signals to external devices such printed circuit boards (PCBs). Besides, the chip can be mounted onto the carrier through a plurality of bumps to form a ball grid array package in a flip chip fashion.
Moreover, another low and thin ball grid array package, such as a chip scale package (CSP) is provided to meet the requirement of the package with a lower profile. However, no matter what the type of the ball grid array package is, the manufacturing method of a conventional ball grid array package mainly comprises following steps. Firstly, as shown in FIG. 1, a carrier unit 11 is provided, wherein the carrier unit comprises a chip pad 112, contacts 114 encompassing the chip pad 112. Next, a chip 12 is disposed on the chip pad 112 and fixed on the chip pad 112 by curing an adhesive (not shown), such as silver paste. Afterwards, gold wires 13 are wire-bonded to the contacts 114 and then an encapsulation is provided to encapsulate the chip 12, the contacts 113, the gold wires 114, the surface of the carrier unit 11. Then, a marking process is performed to form a mark on the surface of the encapsulation 14 for identification. Finally, a solder-balls placing process is performed to attach the solder balls 15 to the surface of the carrier unit opposed to the surface carrying the chip 12 so as to complete the packaging process.
Because the carrier unit 11 is usually warped after the encapsulation 14 is formed to cover the chip 12, the solder balls placing process is difficult to perform and the solder balls 15 can not be mounted to the correct locations of the carrier unit 11 due to said warpage of the carrier unit 11. Particularly, the thinner the carrier unit is, the dislocation of the solder balls 15 being disposed on the carrier unit 11 is easily happened.
Therefore, providing another manufacturing method of ball grid array package to solve the mentioned-above disadvantages is the most important task in this invention.